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hotroses

What have I dug up?

hotroses
17 years ago

Finally this weekend I started working on my backyard garden beds! Our house (built in 1920) is in an old neighborhood of Charlotte and the yard is badly neglected. It was a garden at one time, but it looks like it hasn't been touched in twenty years. I spent most of the summer cutting back and digging out volunteer bushes and eradicating poison ivy. Anyway, this weekend I started digging up my beds and found a curious layer of material about 6 inches under the surface. It consists of black gravel and larger chunks (fist sized) of what looks like molten rock with gravel stuck in it. The gravel looks like an old driveway (in the middle of the backyard?) but what are the chunks? Could it have been really old decomposing alphalt? It looks more molten than a compressed asphalt and reminds me of the volcanic chunks I used to dig up in my garden in Portland which was literally on a volcano vent. The gravel is really very fine grained black rocks - is that quarried near here? If this is old asphalt, can I dig it into the garden soil and ignore it or should I avoid digging into it?

On the upside, there is a 5 inch layer of fairly good looking dark soil and it all seems to drain well. If I get deeper than the black gravel layer, I get red and yellow clay which is what I really expected.

If anyone knows about how they used to make driveways or if old asphalt is toxic to plants, I would appreciate your comments!

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